Re-entry guidance method based on decoupling control variables and waypoint

2019 ◽  
Vol 123 (1262) ◽  
pp. 523-535 ◽  
Author(s):  
Z. Li ◽  
T. Yang ◽  
Z. Feng
Keyword(s):  
Vertical Motion ◽  
Decoupling Control ◽  
Horizontal Motion ◽  
Motion Model ◽  
Control Variables ◽  
The Earth ◽  
Entry Guidance ◽  
Trajectory Guidance ◽  
Loss Of Motion ◽  
Control Accuracy

ABSTRACTGenerally, earth rotating and non-spherical perturbation of the earth in re-entry motion model are simplified using the standard trajectory guidance method. The re-entry motion is also simplified to horizontal motion and vertical motion and controlled, respectively. The simplification of re-entry motion model will lead to loss of motion accuracy and location accuracy. The direct decomposition will lead to the reduction of control accuracy because the horizontal motion and the vertical motion are coupled in re-entry. To improve the standard trajectory guidance method, the standard trajectory guidance method based on decoupling control variables and waypoint is proposed in this paper. The proposed guidance method will not simplify earth rotating and non-spherical perturbation of the earth in motion equation or decompose the re-entry motion to horizontal motion and vertical motion. Trajectory waypoint is adopted to reduce the change frequency of tracking states, because tracking states change frequently if the entire standard trajectory is tracked in real time.

Granitoid complexes and the Archean tectonic record in the southern part of northwestern Ontario

1979 ◽  
Vol 16 (10) ◽  
pp. 1965-1977 ◽  
Author(s):  
W. M. Schwerdtner ◽  
D. Stone ◽  
K. Osadetz ◽  
J. Morgan ◽  
G. M. Stott
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Strike Slip ◽  
Horizontal Motion ◽  
Tectonic Deformation ◽  
Northwestern Ontario ◽  
Greenstone Belts ◽  
Second Period ◽  
Transcurrent Faults ◽  
Regional Compression

Two principal, possibly overlapping, periods of tectonic deformation can be distinguished in the Archean of northwestern Ontario, a period of dominantly vertical-motion tectonics and a period of dominantly horizontal-motion tectonics. Gigantic diapirs of foliated to gneissic tonalite–granodiorite developed during the first period and appear to be responsible for the gross structure of, and the major folds within, the metavolcanic–metasedimentary masses ("greenstone belts"). These diapirs are most likely due to mechanical remobilization of early tabular batholiths which originally intruded the oldest supracrustal rocks presently exposed. Later massive to foliated, dioritic to granitic plutons that vary from concordant, crescentic plutons to partly discordant plutons of various shapes and sizes were emplaced into the diapirs.The second period of tectonic deformation is characterized by large-scale dextral shearing and the development of major transcurrent faults under northwesterly regional compression. The strike-slip motions of this period outlasted the late plutonism, and led to the development of mylonitic zones which cut all Archean granitoid plutons.

Motion Characteristics of Composite-Type Sea Cage under Pure Wave

2012 ◽  
Vol 490-495 ◽  
pp. 3405-3409
Author(s):  
Chun Liu Li ◽  
Yun Peng Zhao
Keyword(s):  
Experimental Data ◽  
Wave Height ◽  
Vertical Motion ◽  
Data Acquisition System ◽  
Horizontal Motion ◽  
Wave Condition ◽  
Composite Type ◽  
Motion Range ◽  
Motion Characteristics ◽  
Sea Cage

To study motion range changes with wave condition and motion relationship between cages, physical model experiments were carried out. The authors designed 2 models of composite-type sea cages. Experimental data obtained by the CCD data acquisition system. The experiment results showed that 1.in the same period, horizontal motion range,vertical motion range and inclination changes of float collar increase with wave height; 2.In the same wave height, horizontal motion range of the float collar increases with period; 3.The laws between vertical motion and period are not obvious 4.The laws between inclination changes and period are not obvious 5.Motion range of the first cage along the direction of waves is less than other cages.

scholarly journals Theoretical aspects of the onset of Indian summer monsoon from perturbed orography simulations in a GCM

2006 ◽  
Vol 24 (8) ◽  
pp. 2075-2089 ◽  
Author(s):  
A. Chakraborty ◽  
R. S. Nanjundiah ◽  
J. Srinivasan
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
General Circulation ◽  
Large Scale ◽  
Vertical Motion ◽  
Circulation Model ◽  
Threshold Value ◽  
The Earth ◽  
Static Energy ◽  
The Impact

Abstract. A theory is proposed to determine the onset of the Indian Summer Monsoon (ISM) in an Atmospheric General Circulation Model (AGCM). The onset of ISM is delayed substantially in the absence of global orography. The impact of orography over different parts of the Earth on the onset of ISM has also been investigated using five additional perturbed simulations. The large difference in the date of onset of ISM in these simulations has been explained by a new theory based on the Surface Moist Static Energy (SMSE) and vertical velocity at the mid-troposphere. It is found that onset occurs only after SMSE crosses a threshold value and the large-scale vertical motion in the middle troposphere becomes upward. This study shows that both dynamics and thermodynamics play profound roles in the onset of the monsoon.

A search for constraints on lithospheric net rotation in 2D convection simulations

2021 ◽  
Author(s):  
Suzanne Atkins ◽  
Nicolas Coltice
Keyword(s):  
Reference Frames ◽  
Plate Motion ◽  
Model Parameters ◽  
Motion Model ◽  
Motion Models ◽  
The Third ◽  
The Earth ◽  
Geological Past ◽  
Wide Range ◽  
Third Dimension

<p>Net rotation is the process whereby the entire lithosphere can rotate with respect to the Earth’s mantle. The plates and continents retain their location with respect to each other, but they change their position with respect to global reference frames such as the Earth’s magnetic dipole, and structures in the Earth’s mantle such as plumes and hotspots. Constraining lithospheric net rotation is therefore one factor in building an absolute plate motion model. However, the amount of net rotation occurring at present day is poorly contained, and the drivers of net rotation are very poorly understood. Many absolute plate motion models therefore attempt to minimise net rotation, because there is no way to constrain rotation in the geological past. </p><p> </p><p>In previous geodynamical studies, the presence of thick continents and large viscosity contrasts were found to be controlling factors in the development of net rotation. We investigate the effects of different convection parameters and tectonic states on the magnitude and evolution of net rotation in 2D simulations. The use of 2D simulations allows us to run enough simulations to study a wide range of model parameters. We intend to compare our 2D conclusions with 3D simulations, to investigate how much of a difference the third dimension makes.</p><p> </p><p>We find that net rotation varies on much shorter timescales than any other geodynamic feature. Net rotation is not cleanly correlated with any tectonic behaviours or settings, and that the magnitude and duration is unpredictable. We do however find that the distribution of net rotation within the lifetime of a particular simulation is Gaussian, with standard deviation dependent on the viscosity structure and contrasts of the simulation, in agreement with previous studies. However, in contrast to previous studies, the presence and thickness of continents makes very little difference to the speed of lithospheric rotation, although this may be because we are working in 2D. If the 2D results are also relevant in 3D, net rotation is a continuously varying and unpredictable value, but with a predictable statistical range. This may provide a way to better constrain net rotation for plate motion models.</p>

scholarly journals Quadrotor Formation Strategies Based on Distributed Consensus and Model Predictive Controls

2018 ◽  
Vol 8 (11) ◽  
pp. 2246 ◽  
Author(s):  
Chia-Wei Chang ◽  
Jaw-Kuen Shiau
Keyword(s):  
Formation Control ◽  
Vertical Motion ◽  
Formation Flight ◽  
Horizontal Motion ◽  
Motion Simulation ◽  
Linear Quadratic ◽  
Distributed Consensus ◽  
Consensus Control ◽  
Formation Pattern ◽  
The Given

In this study, the distributed consensus control and model predictive control (MPC)-based formation strategies for quadrotors are proposed. First, the formation-control problem is decoupled into horizontal and vertical motions. The distributed consensus control and MPC-based formation strategy are implemented in the follower’s horizontal formation control. In the horizontal motion, the leader tracks the given waypoints by simply using the MPC, and generates the desired formation trajectory for each follower based on its flight information, predicted trajectory, and the given formation pattern. On the other hand, the followers carry out the formation flight based on the proposed horizontal formation strategy and the desired formation trajectories generated by the leader. In the vertical motion, formation control is carried out using only the MPC for both the leader and the follower. Likewise, the leader tracks the desired altitude/climb rate and generates the desired formation trajectories for the followers, and the followers track the desired formation trajectories generated by the leader using the MPC. The optimization problem considered in the MPC differs for the horizontal and vertical motions. The problem is formulated as a quadratic programming (QP) problem for the horizontal motion, and as a linear quadratic tracker (LQT) for the vertical motion. Simulation of a comprehensive maneuver was carried out under a Matlab/Simulink environment to examine the performance of the proposed formation strategies.

Cloud Patterns as Seen from Altitudes of 250 to 850 Miles — Preliminary Results

1960 ◽  
Vol 41 (6) ◽  
pp. 291-297 ◽  
Author(s):  
John H. Conover ◽  
James C. Sadler
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Time Lapse ◽  
Squall Line ◽  
Low Level ◽  
The Earth ◽  
Stationary Front ◽  
Ballistic Missiles ◽  
High Level ◽  
Cloud Patterns

Time-lapse films of the earth from high-flying ballistic missiles have provided the meteorologist with the first synoptic detailed coverage of cloud patterns over large areas. Analysis of the film obtained on 24 August 1959 shows the cloud patterns over an area corresponding to one-twentieth of the earth's total surface. Comparison of the rectified cloud positions with, the high- and low-level synoptic charts shows large-scale cloud patterns directly associated with high-level vortices and troughs as well as patterns associated with a quasi-stationary front and the intertropical convergence zone. Details suggesting low-level vortices, frontal waves, and a squall line appear, but they cannot be verified due to sparse surface observations. Other details, such as the effects of large and small islands, coastlines and rivers upon the pattern of vertical motion are indicated by the clouds.

scholarly journals The relation between wind velocity at 1000 metres altitude and the surface pressure distribution

1908 ◽  
Vol 80 (540) ◽  
pp. 436-443 ◽  
Keyword(s):  
Angular Velocity ◽  
Pressure Distribution ◽  
Wind Velocity ◽  
Centrifugal Force ◽  
Surface Pressure ◽  
Atmospheric Pressure ◽  
Horizontal Motion ◽  
Radius Of Curvature ◽  
Surface Pressure Distribution ◽  
The Earth

For the steady horizontal motion of air along a path whose radius of curvature is r , we may write directly the equation (ω r sin λ ± v ) 2 / r = 1/ρ ∂ p / ∂ r +(ω r sin λ ) 2 / r , expressing the fact that the part of the centrifugal force arising from the motion of the wind is balanced by the effective gradient of pressure. In the equation p is atmospheric pressure, ρ density, v velocity of moving air, λ is latitude, and ω is the angular velocity of the earth about its axis.

scholarly journals Spheroidal free periods of the earth observed at eight stations around the world

1964 ◽  
Vol 54 (2) ◽  
pp. 755-776
Author(s):  
L. E. Alsop
Keyword(s):  
Phase Velocity ◽  
Rayleigh Waves ◽  
Vertical Motion ◽  
Present Theory ◽  
Period Range ◽  
Moving Source ◽  
The Earth ◽  
Spectral Peaks ◽  
The World ◽  
Different Parts

ABSTRACT Spectral peaks corresponding to the spheroidal free periods of oscillation of the earth exist in the spectra of eight seismograms written at stations in different parts of the world shortly after the great Chilean earthquake of 22 May 1960. These data have been combined with those previously reported by various authors to obtain a very precise phase velocity vs period curve for Rayleigh waves in the period range of 200 to 3200 seconds. The observed spectral amplitudes lend some support to the assumption of a moving source, but they also indicate that the present theory is not adequate. The vertical motion is found to be symmetric with respect to reflections through the pole.

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